Electric fuse



June 29, 1943. E. w. GARRISON, JR 2,323,213

ELECTRIC FUSE Original Filed Dec. 16, 1940 2 Sheets-Sheet 1 INVENTOR June 29, 1943.

E; w. GARRISON, JR ELECTRIC Fusr Original Filed Dec. 16, 1940 2 Sheets-Sheet 2 v INVENTOR Patented June 29, 1943 ELECTRIC -FU SE Edgar W. Garrison,

signor to Southern Jr., Birmingham, Ala., as,-

States Equipment Corporation, a corporation of Alaba Substituted for abandoned application Serial No.

370,261, December One of the purposes of the invelltion is to provide a type of electric fuse suitable for service at high voltage which will operate more cerview of the latch-hood nembers in larger scale; Fig. 4 is a side view of he latch; Fig. 5 shows the hinge members when he device is opened; and Figs. 6 and 7 show two 'iews of one of the many variations which may re made in designs embodying the invention.

The support I carries the insulators 2, 3 upon rhich are mounted the top casting 4 and the linge casting 5, line,connections being made at and l. The removable expulsion-tube 8 conains the fuse-link 9 the cable-ends of which re secured to the hinge terminal l and the itch II. The latch II is pivoted at I 2 to the ip terminal i3, and the cylindrical surface'of I makes contact with the spring contact finger l, which is fastened to the top casting 4. The (is of the cylindrical surface on H and the vet l2 are preferably coincident.

A somewhat similar finger I is secured to the akes contact with ter- The trunnions iii are flattened on 1e side, so that they can be lifted out of the nge 5 only when the tube 8 is in the open siti'on indicated by dotted lines in Fig. 2, and own also in Fig.5.

The latch II has two side projections I'l. iese are engaged by the lower ends of the ridges which extend inwardly along the lower edges the latch-hood i9 which is pivoted at 20 to a top casting 4, and which is biased downrdly by the spring 2|. A suitable stop limits a downward motion of the hood I9. A spring biases the latch ll upwardly towards the ;it on shown in Fig. 2 and Fig. 4. Vhen in closed circuit position shown in l, the trunnion I6 is locked against lifting vardly out of its bearings in the base 5, and

upward pressure of contact finger l5 against solid hinge terminal in biases the tube 8 wardly away from its closed circuit position. 2 sides of hood I! rest against top casting 4, can in Fig. 3, and limit the downward motion 16, January 1. 1942. Serial No.

. r aClaims. -(01. 200-114) 1940. This application of hood IS. The finger I4 presses outwardly against latch II and so holds the projections H, il securely against the ridges I8. There is neither upward nor downward pressure exerted against any part of latch H by any member supported on insulator 2. The point of contact betwen finger l4 and latch H, the projections IT and the pivot I 2 are all substantially the same radial distance from the pivot at trunnions I 6, and an external force tending to pull the tube 8 open would therefore exert no increased pull upon the fuse-link 93 nor does the pressure of finger it nor the holding pressure of I 8 against I! tend to rotate the latch I I, but it is rotated solely by the spring 22 after the fuse-link has ruptured.

Operation is as follows: When the fuse-link ruptures at 9 due to overload, the spring 22 swings the latch l l and the upper half of the fuse-link cable upwardly. As the latch pivots about the pin I2, the cylindrical surface of the latch remainsin sliding contact with the finger contact I 4 until the projections I! have become disengaged from the ridges i8. At the same time the cable end is jerked upwardly and a wide gap is established in the circuit within the tube 8, which aids the arc expulsion effect. With I! disengaged from IS, the pressure from the fingers It and i 5 tends to rotate the tube 8 around its trunnions l6, and the tube starts its downward swing towards the fully opened positioned indicated by dotted lines in Fig. 2.

When the fuse is to be replaced, .the tube is hinged support, a new fuselink is properly installed, the inverted tube is replaced in its hinges and the tube is swung outwardly and upwardly. Thereupon the trunnlons become held by the hinge member 5 so that pressure from the contact finger I5 does not dislocate the hinge joint.

As the projections ll en faces of the two ridges I8, the whole hood I9 is raised, against the bias of spring 2|, until the projections I! have reached the ends of ridges l8. Then the hood i9 snaps downwardly and the ridges l8 then hold the device in closedcircuit position as shown in Fig. 1. Meanwhile the finger I 4 has been forced inwardly, and in closed-circuit position It exerts considerable pressure against the cylindrical surface of latch ll.

gage the under sur- Whenever it is desir manually, the hood l9 sulated means. the projections ed to open the device is lifted by suitable in- This lifts the ridges l8 up above I1, and pressure from the spring fingers I4 and. swing the tube 8 outwardly so that it immediately drops by gravity to the fully opened position.

The parts are so proportioned that the pressure of the spring finger ll and the holding effect of the ridges l8 against the projections l1 produce a resultant force that does not tend to rotate the latch Ii around its pivot l2. Thisis partlydue to having the plane of contact between II and the cylindrical surface of ii closely adjacent to the pivot l2. Another factor is that, as seen in Fig. 1, the contact between the finger l4 and the cylindrical surface of II, the contacts between the projections II and the ridges l8, and the axis of the pivot II, are all closely adjacent to a single plane that is substantially perpendicular to a plane that passes through the axis of the hinge at I! and the axis of the pivot l2. In normal use the parts are not lubricated aind therefore friction will counterbalance the effect of slight variations from the proportions as described.

Thus, even if the tube is violently closed in and there is a consequently hard reaction outwardly, there is no serious strain tending to rotate ll about its pivot 12. Therefore there is no excessive strain tending to break the fuselink ,9. Substantially the only strain upon the fuse-link 9 is that imposed by the spring 22. Thismeans of reducing the shock on the fuselink is one of the important features of this invention. Another advantage of this design is that even though sleet might freeze the hood I! against motion about its pivot 20, the latch H could still rotate and so release the tube 8 from its closed circuit position.

A modified design which still includes this invention is shown in Figs. and 6, where the hood 23 carries the fork 24 which is pivoted at 25 and is biased downwardly by the spring 26. Suitable stops limit the travel of the fork 24. Operation is similar to that of the other design, except that, as the fused tube is being closed, the fork 24 rotates about pivot 25 without the necessity of motion of the hood 23 about its pivot.

Other modifications also may be made by one familiar with the art without departing from the spirit and purpose of the invention.

I claim:

1. In an electric fuse, two spaced insulated terminals, an expulsion fuse tube held by a pivotal mounting upon one of said terminals and held by a latch mechanism in contact with the other said terminal, and a fuse-link within the tube and completing the circuit therethrough; the said latch mechanism including a terminal member supported on the said other terminaland a movable member supported movably upon the said fuse tube, these said latch members when in normal closed circuit position engaging one another -only by pressure substantially transverse to the length of the tube, and the said pressure exerting substantially no strain on the said fuse link.

2. In an electric fuse, two spaced insulated terminals, an expulsion fuse tube held by a pivotal mounting upon one of said terminals and held by a latch mechanism in contact with the other said terminal, and a fuse-link within the tube and completing the circuit therethrough; the said latch mechanism comprising' a latch piece pivotally mounted upon the fuse tube, a spring which biases the latch piece to rotate about its pivotal mounting towards its releasing position, the said rotation being prevented by tension on the fuse-link, a contact surface on the latch piece substantially cylindrical about its pivotal mounting, a spring contact member biased outwardly against the said cylindrical contact surface, and a holding member on the other said terminal cooperable to engage the said latch piece.

3. In an electric fuse, two spaced insulated terminals, an expulsion fuse tube held by a pivotal mounting upon one of said terminals and held by a latch'mechanism in contact with the other said terminal and a fuse-link within the tube and completing the circuit therethrough; the said latch mechanism including a latch piece mounted by a pivot upon the fuse tube and with two lugs which project outwardly beyond the said pivot, a protective hood above the latch piece supported by the said terminal and with parts engageable with the said two lugs to hold the fuse in closed circuit position.

4. In an electric fuse, two spaced insulated terminals, an expulsion fuse tube held by a pivotal mounting upon one of said terminals and held by a latch mechanism in contact with the other said terminal, and a fuse-link within the tube and completing the circuit therethrough and holding a latch piece in normal position; the said latch mechanism including the said latch piece which is pivotally mounted upon the fuse tube and has a holding lug, a spring member biasing the latch piece to rotate and move the said lug towards the pivotal mounting of the fuse tube, together with a movable member supported by the said other terminal and cooperable with the said lug to hold the fuse tube in closed circuit position without thereby imposing any strain upon the said fuse link except that caused by the said spring member.

5. In an electric fuse, two spaced. insulated terminals, an expulsion fuse tube held by a pivotal mounting upon one of said terminals and held by a latch mechanism in contact with the other said terminal, and a fuse-link within the tube and completing the circuit therethrough; the said latch mechanism including a movable latch piece mounted on the fuse tube and with two lugs thereon, a movable hood mounted on the said other terminal and having a pair of holding parts under the hood and engageabl with the said lugs to hold the fuse tube in closed circuit position.

6. In an electric fuse, two spaced insulated terminals, an expulsion fuse tube held by a pivotal mounting upon one of said terminals and held by a latch mechanism in contact with the other said terminal, and a fuse link within the tube and completing the circuit therethrough; the said latch mechanism including a movable latch piece mounted on the fuse tube and with two lugs thereon movable towards the pivotal mounting of the fuse tube, a .hood mounted on the said other terminal, a pair of movable holding parts under the hood and engageable with the said lugs to hold the fuse tube in closed circuit position.

7. In an electric fuse, two spaced insulated terminals, an expulsion tube held by a pivotal mounting upon one of said terminals and held by a latch mechanism in contact with the other said terminal, and a fuse-link within the tube and completing the circuit therethrough; the said latch mechanism including a holding member supported upon the said other terminal, a latch piece pivotally mounted upon the fuse tube, a spring which biases the latch piece to rotate about its pivotal mounting towards its releasing tube and completing the circuit therethrough; position, the said rotation being prevented by the said latch mechanism including a holding tension on the fuse-link, .the said latch member member mounted on the othersaid terminal, a and the said holding member when in normal latch piece movably supported on the tube and closed circuit position engaging one another by 5 with a holding part that is engageable with the pressure in a plane substantially transverse to said holding member to keep the fuse in closed the length of the tube. circuit position, the said holding part being 8. In an electric fuse, two spaced insulated biased towards the pivotal mounting of the tube terminals, an expulsion fuse tube held by a and engaging the said holding part with prespivotal mounting upon one of said terminals and 10 sure that is in a plane approximately transverse held by a latch mechanism in contact with the to the length of the expulsion tube. other said terminal, and a fuse link within the EDGAR W. GARRISON, JR. 

